In touch sensors such as a touch screen and a touch pad, input is made by contact of a finger, a pen, or the like onto a screen, without using input devices such as a keyboard or a mouse. Although a touch screen needs to be improved with respect to accuracy, an input speed, input of characters, and so on, it is advantageous in that it enables anybody to easily make input. Thus, the touch screen has been conventionally used in public sectors such as an automated teller machine, Kiosk, and the like. However, with the recent development of the mobile communication technology, the touch screen has extended its function to means for simply displaying character information in electronic information devices such as mobile phones, PDAs, and navigation systems, and furthermore, means for providing more various and complicated multi-media in audios, videos, and wireless internet web browser. As the multi-media function is developed, realization of a larger display screen within a restricted size of an electronic information device is being demanded. Accordingly, a display using a touch panel is being more spotlighted.
Since a touch display formed by stacking a touch panel on a liquid crystal display integrates a screen and a coordinate input means, it is advantageous in reduction of space, compared to a conventional key input type. Accordingly, since an electronic information device, to which the touch display is applied, can increase a screen size and improve user convenience, the use of the touch panel is being increased.
To briefly review detection types, there are a resistive type, which detects a position pressed by a pressure by means of change in a current or voltage value in the state that a DC voltage is applied, a capacitive type, which uses capacitance coupling in the state that an AC voltage is applied, and an electromagnetic type, which detects a selected position by means of change in a voltage in the state that a magnetic field is applied.
The resistive type is combined with a liquid crystal display device to be adopted for personal mobile devices, navigation systems, PMPs, electronic notebooks, PDAs, and so on. The resistive type of a touch panel is divided into an analogue type and a digital type depending on a method of detecting a touch point. Korean Patent Application Publication No. 2008-0108277 describes a method for production of a resistive touch sensor using ultrasonic wave fusion.
As described above, various types of touch screens are being provided in various devices. However, there are problems that should be solved for reduction of costs and improvement of performance. That is, a touch screen device having a more simplified structure and a more improved performance is demanded. Further, conventional touch screen devices have a problem in that it is difficult to realize large size screens.